We have studied the magnetic and electronic properties of Cu2-xZnxV2O7 by magnetization, specific heat, and dielectric measurements. X-ray structural analysis shows a Zn-mediated phase transition from the α- to the β-phase beyond a critical Zn concentration of xc = 0.15. While Cu2V2O7 exhibits a canted antiferromagnetism with an associated weak ferromagnetism in the α-phase, the β-phase is purely antiferromagnetic. The spin canting arises due to the Dzyaloshinskii-Moriya exchange interaction in the anti-symmetric α-phase. The temperature dependence of the heat capacity for the sample in the α-phase shows a clear lambda like transition at a temperature where the magnetic susceptibility also displays an anomaly and indicates an onset of long range magnetic ordering. Dielectric properties display a clear anomaly around the magnetic transition temperature in α-Cu2V2O7. The anomaly weakens with the increase in the Zn concentration and disappears at the doping level where α to β phase transition occurs. This confirms the existence of magneto-electric coupling in α-Cu2V2O7 but not in its β-phase. Analysis of the experimental data shows that magneto-electric coupling is non-linear in nature, which is in agreement with the Landau theory of continuous phase transition. So, α-Cu2V2O7 establishes itself as a promising candidate for magnetic multiferroics.

To establish intrinsic ferromagnetism (FM) and to detect its micro-structural origin (if any), sol-gel derived Zn 0.95 Mn 0.05 O films have been undergone low energy (800 keV) Ar 4+ ion irradiation. The structural, optical, magnetic and micro-structural properties of irradiated and un-irradiated films were investigated by X-ray diffraction (XRD), UV-visible and photoluminescence (PL) spectroscopy, field and temperature dependent magnetization measurements, X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy. All the films exhibit single-phase wurtzite structure and intrinsic FM. The band gap and band tail parameters show systematic variation with fluence of irradiation.PL spectra exhibit a green emission peak (oxygen vacancy) and that has been suppressed significantly for

No abstract

No abstract

The (BH)max value of 2.41 MGOe at room temperature confirmed the capabilities of CoFe2O4 NPs in permanent magnets for current technological applications.